Variable Displacement Compressor

ABSTRACT

Variable displacement compressor comprising a housing; piston; and drive shaft rotatably supported by the housing; a rotor rotating in unison with the drive shaft; a swash plate that rotates in synchronism with the rotation of the connected rotor. Rotation of the swash plate is converted into a reciprocating motion of the piston; and a pressure control valve that is capable of controlling the internal pressure of a crank chamber. The swash plate is connected to the rotor in an inclined fashion such that, as viewed from a site on the swash plate corresponding to the top dead center position of the piston, a compression process region toward the positive direction of the rotation of the swash plate is farther away from the bearing surface of a thrust bearing, which is formed on the rotor, than a suction process region toward the negative direction of the rotation of the swash plate.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a variable displacement compressor, which is specifically used in an air-conditioning system for vehicles.

BACKGROUND ART OF THE INVENTION

Patent document 1 discloses a hinge mechanism (link mechanism) connects two component parts as rotatable with a connecting pin. Patent document 2 discloses a technique of providing a relative-movement regulation means to stabilize the swash plate behavior to the drive shaft.

PRIOR ART DOCUMENTS Patent Documents

Patent document 1: JP2003-172333-A

Patent document 2: JP2002-364530-A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the hinge mechanism (link mechanism) disclosed in Patent document 1, if the swash plate inclined from a vertical direction with axial load derived from compressive load, the through-hole of the swash plate inclines to abrade a contact part between the edge of the through-hole and the circumferential surface of the drive shaft, so that the inclination motion of the swash plate cannot be performed smoothly. Such an abrasion may progress particularly at the maximum inclination side of the swash plate because of greater compressive load, so that the inclination motion of the swash plate is blocked.

Accordingly, it could be helpful to provide a variable displacement compressor in which abrasion of a contact part between the through-hole of the swash plate and the circumferential surface of the drive shaft is prevented and the inclination motion of the swash plate is performed smoothly.

Means for Solving the Problems

To achieve the above described object, the present invention is a variable displacement compressor comprising a housing accommodating a discharge chamber; a suction chamber; a crank chamber and a cylinder bore, a piston provided in the cylinder bore, a drive shaft rotatably supported by the housing, a rotor that rotates integrally with the drive shaft, a swash plate that rotates in synchronism with a rotation of the rotor connected through a connecting means, a conversion mechanism that converts a rotation of the swash plate into a reciprocating motion of the piston, and a pressure control valve that is capable of controlling an internal pressure of the crank chamber according to a valve opening, wherein

when the valve opening is changed to change the internal pressure of the crank chamber, a discharge capacity for compressing and discharging a refrigerant sucked from the suction chamber into the cylinder bore is changed by changing a stroke of the piston through changing an inclination of the swash plate to the drive shaft while the swash plate slides on the drive shaft, characterized in that

the swash plate is connected as inclined from the rotor so that a compression process region at a side of a positive rotation direction of the swash plate is located away from a backup face of a thrust bearing formed on the rotor further than a suction process region at a side of a negative rotation direction of the swash plate, as viewed from a position corresponding to a top dead center position of the piston.

When such a variable displacement compressor is operated to apply compressive load to the swash plate, the side of the through-hole contacts the circumferential surface of the drive shaft in a manner like a line contact, so that abrasion of a contact part between the through-hole of the swash plate and the circumferential surface of the drive shaft is prevented and the inclination motion of the swash plate is performed smoothly.

It is preferable that a ratio of a distance of the compression process region of the swash plate from the backup face of the thrust bearing to another distance of the suction process region from the backup face is maximum as viewed from the position corresponding to the top dead center position when the inclination is maximum. With such a configuration, the compressive load decreases as the inclination decreases from the maximum inclination corresponding to the maximum compressive load, so that the side of the through-hole contacts the circumferential surface of the drive shaft in a manner like the line contact regardless of the swash plate inclination of the variable displacement compressor in operation.

It is preferable that a minimum inclination angle of the swash plate is set to almost 0° and a ratio of a distance of the compression process region of the swash plate from the backup face of the thrust bearing to another distance of the suction process region from the backup face is minimum as viewed from the position corresponding to the top dead center position when the inclination is minimum. When the minimum inclination angle is almost 0°, the compressive load works too little to incline the swash plate unnecessarily.

Effect According to the Invention

The present invention can provide a variable displacement compressor capable of making a smooth inclination motion with a simple structure.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a longitudinal section view showing a variable displacement compressor according to an embodiment of the present invention.

FIG. 2 shows the link arm in FIG. 1, where (a) is a top view and (b) is an arrow view from A direction shown in (a).

FIG. 3 is an arrow view showing a connected body of the drive shaft and rotor in FIG. 1.

FIG. 4 is an arrow view showing the swash plate in FIG. 1.

FIG. 5 is a front view showing a connected body of the drive shaft, rotor, link arm and swash plate in FIG. 1.

FIG. 6 is a plan view of the swash plate viewed from the rotor side in FIG. 1.

FIG. 7 is a partial plan view showing a connected body of the second connecting pin and swash plate in FIG. 6.

FIG. 8 shows the positional relation among rotor, drive shaft, link arm and swash plate, where (a) is a plan view of the connected body of the drive shaft and rotor, (b) is a front view showing the link arm, and (c) is a plan view of the swash plate.

FIG. 9 explains an inclination angle of the swash plate in FIG. 1, where (a) shows a condition of the maximum inclination and (b) shows another condition of the minimum inclination. In each of (a) and (b), an arrow view of a second connecting pin viewed along C2 or C1 direction is on upper left, an arrow view of a swash plate viewed along B2 or B1 direction is on upper right, and a side view of a connected body is below.

FIG. 10 is a schematic side view of the swash plate for explaining an inclination when the variable displacement compressor in FIG. 1 is operated.

FIG. 11 is a partial enlarged schematic section view of an enlarged contact part between the swash plate and drive shaft in FIG. 8.

FIG. 12 is a plan view of a swash plate viewed from a rotor side of a variable displacement compressor according to another embodiment of the present invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

A variable displacement compressor according to the present invention can be explained visually with referring to virtual planes (planes P1-P3) as follows. The present invention is a variable displacement compressor comprising a housing having compartments of a discharge chamber; a suction chamber; a crank chamber and a cylinder bore, a piston provided in the cylinder bore, a drive shaft rotatably supported by the housing, a rotor that is fixed to the drive shaft to rotate integrally with the drive shaft, a swash plate that is attached as slidably contacting to the drive shaft through a through-hole in which the drive shaft is inserted to rotate in synchronism with the rotor connected through a connecting means to change an inclination from an axis line of the drive shaft, a conversion mechanism that converts a rotation of the swash plate into a reciprocating motion of the piston, and a pressure control valve that is capable of controlling an internal pressure of the crank chamber, wherein an opening of the control valve is adjusted to change the internal pressure of the crank chamber, a stroke of the piston is adjusted through changing the inclination of the swash plate, and a refrigerant sucked from the suction chamber into the cylinder bore is compressed and discharged to the discharge chamber, characterized in that

a plane P2, defined as an annular plane of the swash plate, is inclined at a predetermined angle with respect to a plane P3 so that a connected body of the drive shaft, the rotor, the connecting means and the swash plate has an outermost part of the plane P2 in a compression process region being located away from a backup face of a thrust bearing formed on the rotor further than another outermost part symmetrical of the plane P2 in a suction process region, wherein

the swash plate is sectioned into the compression process region and the suction process region by a plane P1 that includes an axis line and a top dead center position of the swash plate while the plane P3 is orthogonal to the plane P1 and includes an intersection line between the plane P1 and the plane P2.

When such a variable displacement compressor is operated to apply compressive load to the swash plate, the side of the through-hole contacts the circumferential surface of the drive shaft in a manner like a line contact, so that abrasion of a contact part between the through-hole of the swash plate and the circumferential surface of the drive shaft is prevented and the inclination motion of the swash plate is performed smoothly.

It is preferable that the predetermined angle decreases as the inclination of the swash plate decreases from a maximum inclination corresponding to a maximum value of the predetermined angle. With such a configuration, the compressive load decreases as the inclination decreases from the maximum inclination corresponding to the maximum compressive load, so that the side of the through-hole contacts the circumferential surface of the drive shaft in a manner like the line contact regardless of the swash plate inclination of the variable displacement compressor in operation.

It is preferable that a minimum inclination angle of the swash plate is set to almost 0° and the predetermined angle corresponding to the minimum inclination angle is almost 0°. When the minimum inclination angle is almost 0°, the compressive load works too little to incline the swash plate unnecessarily.

Hereinafter, desirable examples of the variable displacement compressor will be explained with reference to the figures.

(1) Variable Displacement Compressor

In FIG. 1, variable displacement compressor 100 as a clutchless compressor comprises cylinder block 101 having cylinder bores 101 a, front housing 102 provided at one end of cylinder block 101 and cylinder head 104 provided with valve plate 103 at the another end of cylinder block 101.

Swash plate 111 is provided around the middle of drive shaft 110 that crosses crank chamber 140 sectioned by cylinder block 101 and front housing 102. Swash plate 111 is provided with through-hole 111 a in which drive shaft 110 is inserted, and through hole 111 a is formed such that swash plate 111 is tiltable between the maximum inclination angle and the minimum inclination angle with axle K orthogonal to a plane that includes the top dead center of the swash plate and the axis line of the drive shaft and is orthogonal to the annular plane of swash plate 111. Swash plate 111 is connected to rotor 112 attached to drive shaft 110 through link mechanism 120 and the side surface of through-hole 111 a is slidingly supported by the circumferential surface of drive shaft 110 to make inclination angle θ variable.

Through-hole 111 a is provided with a minimum inclination regulation part brought into contact to drive shaft 110. In the example, the minimum inclination regulation part of through-hole 111 a is configured to have a swash plate inclination angle θ of almost 0° if the annular plane of swash plate 111 orthogonal to drive shaft 110 is assumed to have 0° of swash plate inclination angle. The said minimum inclination angle of almost 0° means that the minimum inclination angle is more than −0.5°, and less than 0.5. It is preferable that the minimum inclination angle is set to 0° to less than 0.5°.

Inclination-decreasing spring 114 as a compression coil spring biasing swash plate 111 down to the minimum inclination angle is provided between rotor 112 and swash plate 111, while inclination-increasing spring 115 as a compression coil spring biasing swash plate 111 up to predetermined inclination angle less than the maximum inclination angle is provided between swash plate 111 and spring support member 116. Because the biasing force of inclination-increasing spring 115 is designed as being greater than the biasing force of inclination-decreasing spring 114, swash plate 111 is positioned to have a predetermined inclination angle so that the resultant force of the biasing force of inclination-decreasing spring 114 and the biasing force of inclination-increasing spring 115 is zero when drive shaft is not rotating.

One end of drive shaft 110 penetrates boss part 102 a projecting out of front housing 102 to extend outward, to be connected to a power transmission device not shown. Shaft seal device 130 is interposed between drive shaft 110 and boss part 102 a to block off the inside from the outside. Drive shaft 110 and rotor 112 are supported in a radial direction with bearings 131 and 132 and supported in a thrust direction with bearings 133 and thrust plate 134. A power is transmitted from an external drive source to the power transmission device to rotate drive shaft 110 in synchronism with the rotation of the power transmission device. The gap between thrust plate 134 and drive shaft 110 to contact thrust plate 134 is adjusted to a predetermined distance with adjusting screw 135.

Piston 136 is provided in cylinder bore 101 a and the outer periphery of swash plate 111 is housed in an inner space of an end of piston 136 projecting toward crank chamber 140. Swash plate 111 is designed to coordinate with piston 136 through pair of shoes 137. Thus piston 136 can reciprocate in cylinder bore 101 a as swash plate 111 rotates.

Cylinder head 104 is sectioned into suction chamber 141 at the center and discharge chamber 142 annularly surrounding radially outer part of suction chamber 141. Suction chamber 141 communicates with cylinder bore 101 a through communication hole 103 a and a suction valve (not shown) which are formed on valve plate 103. Discharge chamber 142 communicates with cylinder bore 101 a through discharge valve (not shown) and communication hole 103 b which is formed on valve plate 103.

Front housing 102, cylinder block 101, valve plate 103 and cylinder head 104 are fastened with through bolts 105 through a gasket not shown, to form a compressor housing.

In FIG. 1, a muffler is provided on a top of cylinder block 101, the muffler comprising lid member 106 and formation wall 101 b formed on the top of cylinder block 101 which are fastened by a bolt with an seal member not shown. Check valve 200 is provided in muffler space 143. Check valve 200 is provided at a connection part between communication path 144 and muffler space 143 and works in response to the pressure difference between communication path 144 (upstream) and muffler space 143 (downstream). For example, communication path 144 is blocked off when the pressure difference is less than a predetermined value and communication path 144 is opened when the pressure difference is greater than the predetermined value. Thus discharge chamber 142 is connected to a refrigerant cycle at the discharge side of an air-conditioning system via a discharge path comprising communication path 144, check valve 200, muffler space 143 and discharge port 106 a.

Cylinder head 104 is provided with suction port 104 a and communication path 104 b. Suction chamber 141 is connected to a refrigerant cycle at the suction side of the air-conditioning system via a suction path comprising communication path 104 b and suction port 104 a. The suction path linearly extends across a part of discharge chamber 142 from the radially outer part of cylinder head 104.

Cylinder head 104 is further provided with control valve 300. Control valve 300 controls an opening of communication path 145 communicating discharge chamber 142 and crank chamber 140, so that the amount of discharge gas introduced to crank chamber 140 is controlled. The refrigerant in crank chamber 140 flows to suction chamber 141 via communication path 101 c, space 146 and orifice 103 c formed on valve plate 103.

Therefore, the discharge capacity of variable displacement compressor 100 can be controlled variably by changing the pressure in crank chamber 140 with control valve 300 to change the swash plate 100 in inclination (namely, change the stroke of piston 136).

When the air conditioner is operated (namely, variable displacement compressor 100 is in operation), electricity applied to a solenoid embedded to control valve 300 is adjusted based on external signal to control the discharge capacity so that the pressure in suction chamber 141 is adjusted to a predetermined value. Control valve 300 is capable of desirably controlling the suction pressure depending on external environment.

When the air conditioner is not operated (namely, variable displacement compressor 100 is under suspension), electricity applied to the solenoid embedded to control valve 300 is turned off to force communication path 145 open to control the discharge capacity of variable displacement compressor at minimum.

(2) Link Mechanism

Drive shaft 110 is fixed to rotor 112 and pair of first arm 112 a is provided as projecting from rotor 112. In pair of first arms 112 a, one end 121 a of link arm 121 formed in an almost cylindrical shape is guided. First connecting pin 122 as a connection means is inserted into through-hole 112 b formed on first arm 112 a as well as through-hole 121 b formed on one end 121 a of link arm 121, so that link arm 121 can rotate around a shaft center of first connecting pin 122 as being guided by pair of first arms 112 a.

First connecting pin 122 is pressed to be held in through-hole 121 b formed on link arm 121 while a small gap is formed between the circumference of first connecting pin 122 and through-hole 112 b formed on first arm 112 a.

Other end 121 c of link arm 121 is provided with a pair of arms projecting from one end 121 a formed in a cylindrical shape and guides second arm 111 b projecting from swash plate 111 thereinto. Second connecting pin 123 as a connection means is inserted into through-hole 121 d formed on other end 121 c of link arm 121 and through-hole 111 c formed on second arm 111 b, so that link arm 121 and swash plate 111 connected to link arm 121 can rotate relatively around a shaft center of second connecting pin 123. Second connecting pin 123 is pressed to be held in through-hole 111 c of second arm 111 b while a small gap is formed between the circumference of second connecting pin 123 and through-hole 121 d formed on link arm 121.

Link mechanism 120 consists of first arm 112 a, second arm 111 b, link arm 121, first connecting pin 122 and second connecting pin 123. Therefore, swash plate 111, which connects rotor 112 fixed to drive shaft 110 through link mechanism 120 and rotates by receiving rotation torque of rotor 112, can change its inclination along drive shaft 110.

(3) Second Connecting Pin (Inclination Design)

FIG. 5 shows a connected body of drive shaft 110, rotor 112, link mechanism 120 and swash plate 111, viewed from a position facing to link mechanism 120.

The line segment with symbol P1 implies plane P1 including the axis line of drive shaft 110 and the top dead center position (as well as bottom dead center position) of the swash plate. Plane P1 corresponds to the cross section shown in FIG. 1. The said top dead center position of the swash plate means a position of piston 136 at the end of a compression process while the said bottom dead center position means a position of piston 136 at the end of a suction process. Symbol P2 implies annular plane P2 of swash plate 111 while symbol P3 implies plane P3 that includes intersection line G (line segment extending from the top side to the back side of paper) between plane P1 and plane P2 and is orthogonal to plane P1. If swash plate 111 is sectioned into two regions by plane P1, the right side is the compression process side and the left side is the suction process side.

Any side of the annular plane of swash plate 111 can be defined as plane P2.

FIG. 6 shows swash plate 111 viewed from rotor 112. In FIG. 6, symbol U implies plane U that is orthogonal to annular plane P2 of swash plate 111 and includes the top dead center position and the center of both side surfaces of through-hole 111 a while symbol V implies plane V that is orthogonal to plane P2 and includes axle K orthogonal to plane U. The swash plate inclination angle of 0° corresponds to a condition where the line of intersection between plane U and plane V overlaps to the shaft center of drive shaft 110. Plane U substantively corresponds to plane P1 because the upper side corresponds to the top dead center position of the swash plate while the lower side corresponds to the bottom dead center position of the swash plate. The center of second arm 111 b corresponds to plane U.

As shown in FIG. 6, axis line m along the axial direction of through-hole 111 c of second arm 111 b is designed as inclining by angle α around the intersection point on plane U from axis line n that is orthogonal to plane U and intersects with axis line m at the intersection point on plane U. The said axis line n is along the axial direction of through-hole 111 c without the inclination of angle α. As shown in FIG. 7, second connecting pin 123 pressed to be fixed to through-hole 111 c inclines by angle α so that one end on the right side is close to plane V while the other end on the left side is away from plane V. Angle α is practically about less than 0.5° although it is exaggerated in FIG. 5 and FIG. 7. It is preferable that angle α is set to 0.2° to 1°, preferably 0.2° to 0.5°.

Since second connecting pin 123 is parallel to plane P2 at 0° of inclination angle of the swash plate, plane P2 becomes equal to plane P3 at 0° of inclination angle as shown in FIG. 5. Namely, annular plane P2 of swash plate 111 is orthogonal to plane P1.

(4) Through-Hole of Swash Plate (Offset)

Both ends of second connecting pin 123 are inserted to be held in through-holes 121 d of link arm 121, while through-holes 121 d of link arm 121 are parallel to axis line n shown in FIG. 6 and are also parallel to the axis line along through-holes 121 b of the link arm as well as through-holes 112 b of the first arm.

If second connecting pin 123 of a connected body consisting of drive shaft 110, rotor 112, link mechanism 120 and swash plate 111 is inclined, because second connecting pin 123 is held in through-hole 121 d, swash plate 111 rotates counterclockwise around the point of intersection of axis line m and axis line n shown in FIG. 6 within the gap between through-hole 111 a of the swash plate and the circumferential surface of drive shaft 110, so that the suction process side surface of through-hole 111 a is brought into contact to the circumferential surface of drive shaft 110.

If the circumferential surface of drive shaft 110 contacts the suction process side of through-hole 111 a, applied compressive load makes swash plate 111 incline greater and the distance between the contact point and the point of the compressive load becomes greater than that in a case of contacting the compression process side, so that inclination motion of swash plate might not be performed smoothly by frictional force.

Accordingly, the axis line of drive shaft 110 is offset by ΔL from the center of both side surfaces of through-hole 111 a as shown in FIG. 8.

FIG. 8 (a) shows a connected body of drive shaft 110 and rotor 112 viewed from swash plate 111, where symbol T implies plane T that includes an axis line of drive shaft 110 and is parallel to the inner surface (guide surface brought into contact with one end 121 a of the link arm) of first arm 112 a.

Pair of first arms 112 a of rotor 112 are parallel to plane T and distance L1 between plane T and the guide surface of one end 121 a of the link arm of first arm 112 a 1 on the left is slightly greater than distance L2 between plane T and the guide surface of one end 121 a of the link arm of first arm 112 a 2. Namely, the guide surfaces of pair of first arms 112 a are not symmetric from plane T but the center of the guide surfaces of pair of first arms 112 a is offset from plane T toward the left in the figure by ΔL=(L1−L2)/2. ΔL is practically about less than 0.2 mm although it is exaggerated in FIG. 8.

As shown in FIG. 8 (b), link arm 121 has both sides (contact part) at one end 121 a and two guide surfaces of pair of arms 121 c to second arm 111 b, which are provided symmetrically to the center of link arm 121. The center of link arm 121 corresponds to plane U shown in FIG. 8 (c).

Therefore, plane T is offset by ΔL toward the left from the center of both sides of through-hole 111 a, so that the compression process side surface of through-hole 111 c comes to contact the circumferential surface of drive shaft 110 even if second connecting pin 123 is inclined.

(5) Inclination Motion of Annular Plane of Swash Plate

FIG. 9 shows how plane P2 inclines relative to plane P3 when the swash plate changes in inclination. FIG. 9 (a) shows a condition of the maximum inclination and FIG. 9 (b) shows another condition of the minimum inclination. Above the connected body of drive shaft 110, rotor 112, link mechanism 120 and swash plate, second connecting pin 123 and swash plate 111 viewed along the arrow directions are shown schematically.

Second connecting pin 123 is parallel to plane P2 at 0° of minimum inclination of the swash plate and therefore plane P2 is equal to plane P3 as shown on the upper right in FIG. 9 (b). Namely, annular plane P2 of the swash plate is orthogonal to plane P1.

When the swash plate inclination increases up to the maximum inclination, because second connecting pin 123 inclines as shown in FIG. 7, the left end part (suction process side) in FIG. 7 of second connecting pin 123 tends to move away from reference level R of the rotor while the right end part (compression process side) tends to move close to reference level R as shown on the upper left in FIG. 9 (a). Reference level R of the rotor is a backup face of bearing 133.

However, both end parts of second connecting pin 123 are held in through-hole 121 d of the link arm and therefore second connecting in 123 itself cannot incline beyond the gap between second connecting pin 123 and through-hole 121 d. As a result, swash plate 111 inclines opposite to the inclination direction of second connecting pin 123 as shown on the upper right in FIG. 9 (a).

Namely, annular plane P2 of the swash plate inclines by angle β from plane P3 as moving in a direction where the outermost part at the compression process side becomes furthest from reference level R of the rotor while the outermost part at the suction process side becomes closest to reference level R of the rotor. Therefore, the angle between plane P2 and plane P3 is zero if the swash plate inclination angle is 0° and it increases up to angle β as the inclination increases up to the maximum inclination.

When variable displacement compressor 100 operates piston 136 to compress a gas, the compressive load acts on swash plate 111 through piston 136.

If there is no compressive load applied, plane P2 inclines from plane P3 and the compression process side moves away from the reference level of the rotor. If there is a compressive load applied by piston 136 to compress a gas, swash plate 111 inclines and moves plane P2 close to plane P3. Angle α as well as angle β are designed such that plane P2 of the swash plate becomes almost equal to plane P3 in operation around the maximum inclination as shown in FIG. 10 because the compressive load becomes greater in a load condition of the maximum inclination of the swash plate.

Thus plane P2 becomes almost equal to plane P3 if variable displacement compressor 100 is operated in a load condition with great compressive load, and therefore the side of through-hole 111 a contacts the circumferential surface of drive shaft 110 in a manner like a line contact by suppressed inclination of through-hole 111 a as shown in FIG. 11. Therefore, abrasion of a contact part between through-hole 111 a and the circumferential surface of drive shaft 110 is prevented and the inclination motion of swash plate 111 is performed smoothly.

Although plane P2 inclines from plane P3 when no load is applied, the plane inclination decreases if the swash plate decreases its inclination and even compressive load decreases if the swash plate decreases its inclination. Therefore, plane P2 becomes close to plane P3 in operation regardless of the swash plate inclination. Therefore, the side of through-hole 111 a contacts the circumferential surface of drive shaft 110 in a manner like a line contact regardless of the swash plate inclination, so that abrasion of a contact part between through-hole 111 a and the circumferential surface of drive shaft 110 is prevented and the inclination motion of the swash plate is performed smoothly.

Although the above-described example shows the link mechanism as a connecting means, it is possible that the connecting means is a hinge mechanism as disclosed in Patent document 2.

Although the above-described example shows that the first arm of the rotor offsets, it is possible that the link arm or the second arm of the swash plate offsets.

Although the second connecting pin is inclined from the second arm by angle α in the above-described example, it is possible that the second arm is inclined from plane U toward a compression process region by angle α so that axis line m of the second connecting pin inclines from axis line n as shown in FIG. 12. In this case, the second connecting pin is orthogonal to the second arm.

Although the above-described example shows a case of a clutchless compressor, it is possible that the compressor is variable displacement compressor having an electromagnetic clutch, variable displacement compressor of wobble plate type, variable displacement compressor driven by a motor.

INDUSTRIAL APPLICATIONS OF THE INVENTION

The present invention is applicable to a variable displacement compressor for air-conditioning system for vehicles or the like.

EXPLANATION OF SYMBOLS

-   100: compressor -   101: cylinder block -   101 a: cylinder bore -   101 b: formation wall -   101 c: communication path -   102: front housing -   102 a: boss part -   103: valve plate -   103 a, 103 b: communication hole -   103 c: orifice -   104: cylinder head -   104 a: suction port -   104 b: communication path -   105: through bolt -   106: lid member -   106 a: discharge port -   110: drive shaft -   111 swash plate -   111 a: through-hole -   111 b: second arm -   111 c: through-hole -   112: rotor -   112 a, 112 a 1, 112 a 2: first arm -   112 b: through-hole -   114: inclination-decreasing spring -   115: inclination-increasing spring -   116: spring support member -   120: link mechanism -   121: link arm -   121 a: end of link arm -   121 b: through-hole -   121 c: other end of link arm -   121 d: through-hole -   122: first connecting pin -   123: second connecting pin -   130: shaft seal device -   131, 132, 133: bearing -   134: thrust plate -   135: adjusting screw -   136: piston -   137: shoe -   140: crank chamber -   141: suction chamber -   142: discharge chamber -   143: muffler space -   144, 145: path -   146: space -   200: check valve -   300: control valve -   K: axle -   P1, P2, P3, T, U, V: plane 

1. A variable displacement compressor comprising a housing accommodating a discharge chamber; a suction chamber; a crank chamber and a cylinder bore, a piston provided in the cylinder bore, a drive shaft rotatably supported by the housing, a rotor that rotates integrally with the drive shaft, a swash plate that rotates in synchronism with a rotation of the rotor connected through a connecting means, a conversion mechanism that converts a rotation of the swash plate into a reciprocating motion of the piston, and a pressure control valve that is capable of controlling an internal pressure of the crank chamber according to a valve opening, wherein when the valve opening is changed to change the internal pressure of the crank chamber, a discharge capacity for compressing and discharging a refrigerant sucked from the suction chamber into the cylinder bore is changed by changing a stroke of the piston through changing an inclination of the swash plate to the drive shaft while the swash plate slides on the drive shaft, characterized in that the swash plate is connected as inclined from the rotor so that a compression process region at a side of a positive rotation direction of the swash plate is located away from a backup face of a thrust bearing formed on the rotor further than a suction process region at a side of a negative rotation direction of the swash plate, as viewed from a position corresponding to a top dead center position of the piston.
 2. The variable displacement compressor according to claim 1, wherein a ratio of a distance of the compression process region of the swash plate from the backup face of the thrust bearing to another distance of the suction process region from the backup face is maximum as viewed from the position corresponding to the top dead center position when the inclination is maximum.
 3. The variable displacement compressor according to claim 1, wherein a minimum inclination angle of the swash plate is set to almost 0° and a ratio of a distance of the compression process region of the swash plate from the backup face of the thrust bearing to another distance of the suction process region from the backup face is minimum as viewed from the position corresponding to the top dead center position when the inclination is minimum. 